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09.00
Functions – Options
Armature short–
Transistor PWM converters can no longer be electronically braked when the DC
circuit braking
link voltage exceeds a specific value or if the electronics has failed. If the drive
represents a danger when it coasts down, the motor can be braked by short–cir-
cuiting the the armature. The armature short–circuit should be made within the
traversing range of the feed axis. However, it should be initiated at the latest by
the emergency limit switch.
When determining the run–up travel of the feed axis, the friction of the mechani-
cal system and the switching times of the contactors should be taken into ac-
count. In order to prevent mechanical damage, mechanical end stops should be
provided at the end of the absolute traversing range.
For servomotors with integrated holding brake, the holding brake can be simul-
taneously de–energized, in order to generate an additional braking force; this
braking torque is somewhat delayed.
Caution
!
The drive converter pulses must always first be cancelled, before an armature
short–circuit contactor is closed. This prevents the contactor contacts burning
which could destroy the PWM converter.
Warning
!
The setpoint input must always be used for standard operational braking. For
EMERGENCY OFF, terminal 64 at the drive converter should be used to initiate
braking.
Brake resistors
The servomotor braking torque can be optimized in regenerative operation
using an armature short–circuit with adapted external resistor. The resistors
which are required are listed in the motor tables.
The resistors can be ordered from:
Fritzlen GmbH & Co.KG
Gottlieb–Daimler–Str. 61
71711 Murr
Tel.: 07144 / 2724–25
Siemens AG 2000 All rights reserved
SIMODRIVE Planning Guide Motors (PJM) – 11.00 Edition
General Information on AC Servomotors
6SN1197–0AA20
3 Functions – Options
3
ALS/3-33
AL S
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